xe2x80x9cNot applicablexe2x80x9d
xe2x80x9cNot applicablexe2x80x9d
The invention is a machine for producing electricity from a water current while allowing marine animals (fish, otters, turtles, etc.) to swim freely through its center. A provisional application 60/267,078 filing date Feb. 6, 2001 has been filed. Its application would be in dams and other areas where existing hydroelectric turbines are detrimental to or completely stop migration of fish from one side of the dam to the other.
Existing turbine designs such as the xe2x80x9cminimum gap runnerxe2x80x9d by Voith Siemens and Alden Research""s xe2x80x9cfish friendlyxe2x80x9d turbine only address smolt or small hatchlings in their journey downstream through the turbines. Even with a survivability rate of between 90 to 98%, if 2 to 10% are injured or killed at each dam and there are 6 to 10 dams in the system, it still involves a high mortality rate.
Studies have shown that when fish swim through a pipe, they have a tendency to swim in the center of the pipe. With its open center, this machine could have a survivability rate of 100% both directions while increasing power output and reducing downstream turbulence.
The machine is a fish friendly (both directions) hydroelectric turbine to replace existing turbines in dams and to be the turbine of choice for new and proposed dams.
The invention is a cylindrical fixed housing with numerous counter rotating open center blades in its interior. As the water reaches each blade, part is routed through the blades while part passes unrestricted through the blades center open area. The part that flows through the blade causes rotation of the blade. The part that flows through the open area in the center of the blade causes a friction pull on the part flowing through the blade and has an end result of pulling against the back side of the blade which produces additional rotational energy and efficiency in the blade. This process happens repeatedly at each blade in the turbine. The net result is a slowing of the water velocity at each blade while power is being produced. The number of blades necessary to obtain a target flow velocity (one needed for fish migration) usually from 3 to 10 knots would be determined by the head pressure of the dam divided by the flow reduction of each blade.
Two prototype turbines, a 9xe2x80x2 and a 9xc2xdxe2x80x2 diameter blade, have been tested in the St John""s river in Florida by Florida Hydro Power and Light Co., with very positive results. A scuba diver could easily swim through the machine while at full power with no harm being done.
Although both prototypes 1 and 2 were designed and tested for low head applications, the data received from each of them suggests the open center blade is more powerful (efficient) than existing turbine blades.
It is possible if not likely, that the machine, when applied to a high head application could be 100% fish friendly while producing more power than the existing turbines they replace. The harmful pressure changes, supersaturation of oxygen and other gases, disorientation and predation will also be reduced since the turbine creates very little turbulence.